How to add “-l” (ell) compiler flag in CMake

Question

Work on Ubuntu 16

I used g++ main.cpp -lpq command for compiler my small project. Now I use Clion and wanna do same what I do with g++

Answer 1

-lq is not a compiler flag (CFLAGS) but a linker flag.

To pass a library in a CMake project you should use:

target_link_libraries(target_name libraries...)

Note that if you specify 'q' as library the project will link with libq.a or, if you are on windows q.dll.

... in your CMakeLists.txt the correct line to add is:

target_link_libraries(day_g pq)

Note also that when you add a CFLAG you should also "remember" the previous ones that may be added by libraries or by your platform, ie:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -O3")

To check the exact flags cmake is passing to compiler or linker you can always run, from the build directory, the following command:

make VERBOSE=1